The stopper used to retain water and other liquids in sinks, tubs and the like may range from a very simple rubber plug to a relatively complex assembly of levers and linkages through which a mounted plug member may be operated remotely. While inexpensive and effective, the simple rubber stoppers are unattractive and tend to deteriorate after periods of use; also, unless tethered, they tend to be misplaced. The mechanical assemblies, on the other hand, are relatively complex and hence expensive to manufacture; they are also somewhat inconvenient from the standpoints of installation and maintenance. Devices for direct drain installation have also been proposed, such as that which is described in Petursson et al U.S. Pat. No. 3,366,980. While avoiding some of the disadvantages of the prior art approaches, the constructions shown by Petursson et al are not of optimal simplicity, and may tend to obstruct flow excessively. Moreover, the patented device is capable of assuming only two positions (i.e., either fully open or fully closed), and thus is not capable of establishing controlled flow at rates reduced from the maximum.
Accordingly, it is an object of the present invention to provide a novel strainer for controlling liquid flow through the drain of a tub or similar vessel, which is of simple construction and consists of a minimum number of parts, and hence is relatively inexpensive and facile to manufacture.
It is also an object of the invention to provide such a strainer which operates effectively and smoothly between closed and open positions.
Another object is to provide a strainer that permits substantially unobstructed flow at rates that can readily be varied.
Yet another object of the invention is to provide a strainer having the foregoing features and advantages, which is attractive, convenient to install and operate, and can readily be disassembled for cleaning and for replacement of sealing elements, if required.